1. Field of the Invention
The present invention relates to a display device, more specifically to a display device that projects images on a windshield of a vehicle, or on any other surfaces.
2. Cross Reference to Related
The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2004-215746, filed on Jul. 23, 2004, entitled “DISPLAY DEVICE”. The contents of that application are incorporated herein by reference in their entirety.
3. Description of the Related Art
In a typical model of display devices for projecting images on a front window (i.e. windshield) of a vehicle, head up displays (HUDs) have been known. One example of HUDs is equipped with a dichroic mirror in order to efficiently project only colored light sent out from its display segment(s) or the like (refer to Utility Model Application Publication 64-35143). This dichroic mirror selectively reflects red light emitted from heater wires of a vacuum fluorescent display (VFD).
Another example of HUDs is constituted by a member that selectively reflects specific-colored light or makes it pass through, so that an extremely bright projection is obtained (refer to Japanese Unexamined Patent Application Publication 2003-161906). In addition, further example of HUDs is provided with coating layers that selectively reflect specific-colored light for the purpose of preventing the deterioration or wash-out of its display section due to ambient light (refer to Utility Model Application Publication 4-101581).
In the above display devices, it has been demanded that the color purity of projected light is improved so that clear images appear on a screen. However, the display section of the display devices may be affected by ambient light. To give an example, when an infrared ray or visible light contained in ambient light is irradiated on a display section, it may deteriorate because of heat generated by the irradiated light. This becomes a serious problem.
In order to meet the demand and to overcome the above problem, the present invention has been conceived.